Throttle control in internal combustion engine



Sept. 10, 1940. c. w. DORWIN E1 AL THROTTLE CONTROL IN INTERNAL COMBUSTION ENGINE Fi led Nov. 14, 1938 INVENTORS CLIFF W DORWl/V. BR/NT EDWARDS.

BY mag 08M ATTORNEYS.

Patented Sept. 10, 1940 UNITED STATES mo'r'ru: CONTROL IN INTERNAL M- .nns'rron ENGINE 01in w. Dorwin, Oakland, and Brint Edwards, Hollywood, Oaliifi, assignors of twenty-nine per cent to John F. Tulloch and twenty per cent to George H. Sharp Application November 14, 1938, Serial No. 240,216

4 Claims (Cl. 12365) Our invention relates to a throttle control for internal combustion engines, and more particularly to a means and method of throttling internal combustion engines operating 'on a two 5 stroke cycle, commonly known as two cycle engmes.

Among the objects of our invention are: To provide a means and method of throttling a two cycle engine to prevent back-firing; to provide a means and method of causing a two cycle. engine to idle without back-firing; to provide a novelmeans and method of admitting fuel charges to a two cycle engine cylinder; to provide an improved throttle mechanism for a two cycle en- 1. gine; to provide a means of simultaneously throttling and changing the timing of a two cycle engine; to provide a means and method of controlling a two cycle engine smoothly throughout its entire operating range of speeds and loads;

and to provide a simple means and method of controlling a two cycle engine.

Our invention possesses numerous other objects and features of advantage, some of which, together with the foregoing, will be set, forth in the following description of specific apparatus embodying and utilizing our novel method. It is therefore to be understood that our method is applicable to other apparatus, and that we do not limit ourselves, in any way, to the apparatus of the present application, as we may adopt various other apparatus embodiments, utilizing the method, within the scope of the appended claims.

Referringto the drawing:

Fig. 1 is a diagrammatic view partly in elevation and partly in section, showing a conventionalized two stroke cycle engine equippedwith our invention.

Fig. 2 is a diagrammatic view in perspective of one way by which multi-cylinder engines may be 0 controlled, utilizing our invention.

Fig. 3 is a perspective view of one of theindividual .throttle valves utilized in the device shown in Fig. 2.

Fig. 4 is a partial sectional view of a radial engine throttleembodying our invention.

Fig. 5 is a diagram showing how the throttle illustrated in Fig. 4 may be appliedto multicylinder radial engines. 1

A conventional two stroke engine is, due to its method of induction and throttling, essentially a single speed engine; "that it operates satisfactorily only in a limited speed range, usually near full throttle. At other speeds its ,operation is usually rough, and missing often occurs.

Our method reduces or removes this tendency,

giving the smooth operation at all speeds that is usually associated with four stroke engines of good design.

It is also well known in the art that two stroke cycle engines are diificult to control, as regards speed, by the use of ordinary and conventional throttling means, and it has been found that such engines are particularly hard to control when superchargers are utilized. Prior two stroke cycle engines have a tendency to miss fire when m idling, and along with such miss-firing what is known as back-firing occurs, which is the actual propagation of flame through the gaseous fuel intake system. We have found that the occurrence of miss-firing and back-firing at idling ,15

speeds is due to the fact that with set valve openings or ports into the cylinders, the gas velocities through these openings or ports are lower than the rate of propagation of flame in the gas, particularly when idling with a small throttle opening, thus allowing flame to propagate back through the intake conduits.

Our invention, broadly, provides for the propressive reduction in size of the valve openings into the cylinders at the cylinders to accomplish throttling, together with the use of supercharging means whereby the velocity of the intake gas into the cylinder is at all times, idlingor under power, greater than the rate of propagation of flame in the gas. Under these conditions the 'fiame cannot pass the intake ports to reach the carbureting means at any time.

Our invention may be more fully understood by direct reference to Fig, 1, showing a single cylinder engine equipped with supercharger and 35 throttle. Here, an engine cylinder l is mounted in the usual manner on crank case 2. Crank case 2 also carries a crank shaft 4 to which is attached connecting rod 5 atone end thereof, piston 6 being connected to the other end and reciprocating in cylinder I. The engine cylinder is fired by spark plug 1, and piston 6 is provided with the usualdeflectors 8.. Gaseous fuel supply to the engine is supplied, in accordance with our invention, notfrom crank case pressure, which 45 is at the best intermittent, as is customary in two cycle engines, but preferably from a centrifugal supercharging blower l0 having its intake attached to the usual carburetor II and its outlet entering intake conduit l2. A positive pressure- 5 blower with a by-pw isfully equivalent.

An in let port It is provided in cylinder-i, and extending. across .this inlet port is a cylindrical throttle valve l5 cooperating, with good fit, in throttle valve casing l6; Cylindrical throttle 55 and carburetor valve I is provided with a conduit opening I I presented to intake conduit I2, and with a cylinder opening I8 presented to port I4 and therefore to the interior of the cylinder.

In order for the advantages of our invention to be fully realized, throttle valve I5 should be ,placed as close as possible to port I4 and form a part thereof. Cylinder I may be provided with the usual exhaust port ZD and exhaust pipe 2I, as is customary in two cycle engines, or, if desirable, the exhaust may be vented through a mechanically operated valve. As far as our present invention is concerned, it is operative with either type of exhaust mechanism. Throttle valve I5 is operated from the outside by a throttle arm 2I rotated by throttle rod 22, I

The arcuate extent of cylinder opening I8 in throttle I5 is such that at full open throttle, fuel gases will have a straight passage from the supercharger II] into cylinder I, whereas when throttle rod 22 and arm 2| are operated to close the throttle, the cylinder is rotated so that the upper edge 24 of the cylinderopening I8 in throttle valve I5 will rotate downwardly, thereby closing off and reducing the size of the intake port into cylinder I, and at the same time effectively lowering the position of the port with respect to the piston cycle. In other words, the gas passing through the partly closed throttle valve will enter .the cylinder I .at a point lower on the cylinder when the throttle is closed or partially closed than it will when it is wide open. This, as will be discussed later, changes the timing of the intake simultaneously with the reduction in size of the intake port, tending to stabilize idling.

In Fig. 2 .we have shown diagrammatically intake conduit I2 as supplying two separate cylinders I. V Each engine cylinder is provided with athrottle cylinder I5, as shown in Fig. I, except that in this case the hollow center of the cylinder opens into an intake manifold 26. Each throttle cylinder is provided with an arm 2'! inside of the intake manifold 26, and all cylinders. are rotated simultaneously by rod arms 29 attached to intake manifold throttle rod 30, which is connected to throttle arm 2| and operating rod 22 outside of the manifold. Springs 29 oppose arms 28 thereby returning the throttle arm 21. Thus, each cylinder is independently throttled. In this case intake conduit I2 is attached to supercharger I0 I'd exactly as was the single cylinder in Fig. 1.

In Fig 4 we have shown a modification of our variable inlet port which comprises a sliding valve 3I reciprocating in a valve casing 32. Here again, the central aperture of this sliding valve has two openings, the cylinder opening 24 and an intake opening II. In case this type of valve is utilized in conjunction with a rotary engine, for which it is ideally adapted, each cylinder is provided.

with a separate valve and casing, and each valve is provided with an end projection 34 having a pin 35 thereon entering angular slots 36 on a valve operating disc 31, rotating concentrically with the crank shaft I of the rotary engine. Valve casing 32 is prolonged in this case to form a manifold casing 39 common to all valve intake openings II, which casing in turn is supplied by inlet pipe I2 from supercharger I0 and carburetor II. Rotation of disc 31 moves the sliding valve 3I in the casing 32 and changes the vertical dimension only of the inlet port I4. It is to be noted that in this case,.as in the embodiment shown in Fig. 1, it. is only the upper limit of the port which is moved, thereby changing the relative position of the inlet port with respect to the piston cycle, thus changing the timing of the inlet charge into the cylinder.

In observing the operation of the throttle it will be seen that the type of throttling obtained,

' utilizing our invention, is quite different from the use of any throttle removed from the inlet port. Here, the throttle valve forms an actual portion of the inlet port, and by means of this valve the inlet port is changed in size. Therefore, if the supercharger I0 is so driven as, for example, by gears 4|] from the engine itself or from an auxiliary source of power, such as an electric motor,

as to supply gasified fuel to the inlet port at The essence of our invention, therefore, re-

sides in providing a throttle mechanism at the cylinder walls which reduces the size of the inlet port as the amount of gas supplied to the engine is reduced for throttling purposes, thereby preventing the velocity of the gas from lowering to a value which would allow propagation of the flame through and past the inlet port. By thus changing the size of the port simultaneously with the reduction of the amount of gasified fuel admitted to the cylinder, flame is prevented at all times from entering the intake system from the cylinder. Actual tests have proven that a two stroke cycle engine operated with the throttling means herein described will not back-fire and will idle without miss-fire, because the velocity of the incoming gas, even though it be reduced in amount, is suflicient to cause scavenging, even at low speeds, and to prevent flame propagation through the inlet port.

We claim:

1. In combination with an internal combustion engine having a' cylinder operating on a two stroke cycle and having an exhaust port, an inlet port for said cylinder, an inlet conduit connected to said port, a valve positioned in said conduit adjacent said port, said valve having an aperture therethrough for gas passage, means for shifting said valve to change the effective area of said port, and means for supplying gasified fuel to said inlet conduit and through said port ata velocity greater than the velocity of flame propag'ation in the reverse, direction, for all adjustments of said inlet port.

2. In combination with an internal combustion engine having a cylinder operating on a two stroke cycle and having an exhaust port, an inlet port for said cylinder, an inlet pipe connected to 'said port, a cylindrical valve positioned in said pipe with the axis of said valve substantially at right angles to the axis of said cylinder and having the periphery thereof in the plane of said ll. Apparatus in accordance with claim 2. wherein the said engine has a plurality 0! cylinders each provided with said described valve, wherein each valve is hollow and connected to said inlet pipe and wherein a single throttle rod is provided to operate all of said valves simultaneously.

4. The method oi controlling the intake gas now into a two-stroke cycle engine cylinder. which comprises changing the amount of said flow and synchronously maintaining the velocity of said gas flow into said cylinder at a value above the velocity 01 flame propagation therein.

CLIFF W. DORWIN. BRINT EDWARDS. 

